Method of ammonization



Oct. 14, 1952 P, KA1K|NGER 2,614,040

METHOD OF AMMONIZATION Filed May 1, 1947 NH; 5 UPPLY 101x50 KC] Z7 AND 1151 04 .STILL f/EATE' X l v 4 Y TE RNARY ERT] LI Z ER 1 N V EN TOR. Filly e Kath/yer B Y A ORMY'S Patented Oct. 14, 1952 METHOD: OEAMMONIZATION" Philippe lKaikinger',v Selzaete, Belgium, assignor, to Manufacturesde Produits Chimiques du Nord Etablis'sements Kuhlmann; Paris,

av corporation of France Application Mayl, 1947,,S1erial No.'.'1 4 5,1 89;

In. France February 12, 1947 2Claims; 1.v

The. presentinvention relates. to a. general method of ammonization, more particularly applicableto the preparation of soluble compound fertilizer withhigh fertilizing material contents from. starting materials of current manufacture. It is, well' known that. the neutralization ofv phosphoric acid through ammoniaup to the sec ond.valence.. inclusive requires, if it. is, desired to realize it withv the use of heat in order that the heat evolvedinthe. reaction may be usedat the utmostior. vaI flrizingthe water brought in with. the acid, that thesaturation of said acid should. be achieved in the presence of, a certain excess. of ammonia the, object of which is to create a tensionopposingthe hydrolysis. Now, the neutralization of phosphoric acid upto the above mentionedstage is desirable,,more particularly in. the, manufacture. of. fertilizers, insofar as it would provide at no-increase of cost a carrier for asupplement or increased. concentration,v of

nitrogen.

If the. reaction. is achieved.v in a single, step and in a..continuous manner. as, for example, by.

causing. a, regular currentof ammonia to bubble through a, saturate-r of rather largecapacityreceiving a constant. flow of. phosphoric acid. in a.

quantity which. is stoichiom'etri'cally less. than that. of. the delivered ammonia. the, products which are collected are, onjthe one hand, a thin.

crystalline, concentrated and hot paste and, on the other hand, a vapour containing the am.- monia inexcess, diluted in the quantity of steam which represents, theyield being accounted for,

the calorific equivalent of the energy freed by the conversion. The. weight ratio (ammonia);

(water)v inv the vapour phase; depends, therefore.

on the excess, of ammonia and increases there with.

will be the lower the higher thepressure of. the ammonia. is; consequently, the working temperaturein the vapour, phase will be the lower the, larger, the excess of ammonia is. With. a constant. total pressure and for a given conversion characterized by an acid'having a predeter-.

mined. initialv concentration and av prescribed saturation. rate, the relative excess of. ammonia Now; the. hotter the paste, the. higher its coefii- If. the. operation is. achieved with a, con-. st'ant total pressure, the steam partial pressure.

France, I

2'; cient.0i.hydro1ysis. conseque t y n rd r obtain thedesired saturation rate, that isto sayiv as above mentioned, a hundredpercent'of both the first valences, it is necessary thetotal; work ing pressurehaving. been chosen, to arrange that the partial pressureof the ammonia. is sufiicient; that is, in practice,,higher than the tensionof hydrolysis.

Finally,,for each total pressure, the excess 'of ammonia should befldetermined by experiment, and thustheregime ofv the temperatures'whicm from an acid of a given. concentration, ,lead'sgto, the desiredsaturation rate.

By operating under the, abovementionedcone ditions the ammonizationofthe phosphoric, acid is obtained in an alkaline medium andatacre' duced temperature,

Sucha method canhe appliednot only to the phosphoric acid alonebut'also to, mixturesloi. said acidwith other substances suchas,vv 1. .11: ample, sulphuric acid..

Thus, it can be applied with. advantage-to the ammonization of mixtures which, without. the particular precautions which, characterizeit, he in a non-alkaline medium and at the. normal boiling temperature,,would give riseto. secondary.

reactions of decomposition. or volatilization and submit the equipment usedfor efiecting thereacr' tion to an excessive corrosion. For instance,;b y. using the above mentioned method,,it..i,s possible, to ammonize very readily a mixture of P110539 phoric and nitric acids or nitric acid. atthesame time as phosphoric acid. in; which, potassium, salt, preferably. potassium chloride, has: previ ously beendissolved or stirred in order taprpaxie, a well homogeneous fertilizer in. which allfth'e, necessary fertilizing substances appear in, the desired quantities.

An object of the present invention is top ovide, a method using. the above-explained principlejand, making it possible to perform commercially. and economically. the ammonization of substances; suchas, for example, phosphoric acidintheprese. ence or in' the absence, of other acids, with; or without the previous incorporation, of potashdn, order to manufacture a homogeneous, concene. trated compound fertilizer which. is perfectly soluble in water.

Said method fundamentally. consists inintros. ducing in a continuous manner into a reaction chamber in which a constantfor substantially constant pressure is maintained, on, the, one hand, the substance or substances, to be; amm0-,. nized and, on the other hand, a current offg as eous. ammonia brought into, an intimate, contact;

in said chamber with said substance or substances, in extracting the ammonized products from said chamber in a continuous Or discontinuous manner, and in collecting, in the upper part of said chamber, the mixture of steam and ammonia which escapes and which is submitted to a condensation, possibly accompanied by a distillation, for separating the steam from the ammonia which is recycled into the chamber after the addition, thereto, of a quantity of fresh ammonia equal to the quantity consumed by the reaction, the respective quantities of the ammonized product or products and of ammonia introduced at every moment into the reaction chamber being maintained constant with a proportion of ammonia calculated in order that the partial pressure of said gas in the chamber is decidedly higher than the tension of hydrolysis of the substances which are formed.

The carrying out of the method according to the invention will be explained more particularly in the following description in which reference is made to the appended drawing which shows, by

way of example, the diagram of a plant for the application of the invention to the manufacture of ternary fertilizer, starting from phosphoric acid, nitric acid and potassium chloride.

Said plant comprises supply vats I and 2 adapted for receivin nitric acid and phosphoric acid respectively, and a supply silo 3 adapted for receiving finely ground potassium chloride. The vat I is connected, through a volumetric measuring device 4 of any known type and a siphon 5, to the lower part of an autoclave saturator 5 which is heat-insulated and provided with an inner acidproof coating. The vat 2 is connected, through a volumetric measuring device I similar to the device 4, to a mixer 8 provided with a stirring device 9 and to which leads a conduit I coming from a weight measuring device II insuring the regular and controlled delivery of the potassium chloride contained in the silo 3. The mixer 8 is itself connected to the middle part of the saturator Bthrough a siphon I2.

The bottom of the saturator 6 is provided with a pipe branch I3 for the removal of the reaction products and its upper part is provided with a piping I4 for the removal of the vapours, which piping is connected to a reflux condenser I in which a circulation of cooling water is insured through pipings I6 and IT.

The condensation elements of the condenser I5 are connected in their upper part through a piping I8 to a volumetric booster I 9 which discharges into a piping connected, with interposition of a heat exchanger 2!, to the lower part of the saturator 6. A drain piping 24 leading to the supply vat 2 is connected with the piping I8, into which opens a piping 22 supplying gaseous ammonia and provided with an adjustable reducing valve 23 which can be calibrated to reduce the pressure to that in pipe I 3 which is at a pressure value chosen in advance. Furthermore, said piping I8 is provided at 25 with a pyrometer which controls, in a manner known per se, a delivery regulator 26 inserted in the piping I6 which supplies the condenser I5 with cooling water, said pyrometer and said regulator being combined in order that the quantity of cooling water delivered to the condenser I5 increases directly proportionally to the temperature in the piping I8.

From the lower part of the condensation elements of the condenser I 5 starts a siphon piping 21 which opens into the upper part of a distillation column 28 heated through a steam coil 29.

The admission of the steam to the coil 29 is controlled by a governor 30 itself controlled by a pyrorneter arranged at 3I on a piping 32 starting from the upper part of the column 28 and opening into the piping I4 upstream of the condenser I5. Finally, a piping 33 connects the lower part of the distillation column 28 to the heat exchanger 2I inserted in the piping 20, the liquid brought to said exchanger through said piping being discharged at 34.

The volumetric measuring devices 4 and I, the weight measuring device I I and the booster I9 are driven through a common motor 35, a system of counter-gears 36 insuring the transmission of the movement to the measuring devices 4, I and The said measuring devices are arranged so that the quantities of materials which they deliver respectively are at every moment in a ratio corresponding to the desired proportioning of the quantities of substances to be introduced into the saturator 6.

The so delivered phosphoric acid and potassium chloride are mixed in the mixer 8 from which the mixture is poured through the siphon I2 into the saturator 6 to which the nitric acid delivered through the measuring device 4 is also supplied by the siphon 5. The ammonia which arrives at the saturator 5 through the piping 20 in a hot and practically dry state, as will be seen later on, reacts with the phosphoric and nitric acids and a thin crystalline, homogeneous and hot paste is formed which is taken oil in a continuous or noncontinuous manner through the bottom pipe branch I3 in order to be granulated and dried through the usual means. The heat evolved through the reaction determines the vaporization of a part of the Water supplied by the acids and freed in the course of the neutralization. The quantity of ammonia to be introduced into the saturator at every moment is determined by calculation and by experience in order to permit the neutralization of the phosphoric acid up to the second valence inclusive, which supposes that the partial pressure of the ammonia, in the gaseous phase which is proportional together to the total pressure, to the quantity of injected ammonia and to the delivered quantity of acids, is at every moment higher than the tension of hydrolysis of the bath which is proportional to the temperature.

The obtained vapours which are formed mainly of a mixture of water and ammonia are led to the condenser I5 through the piping I4. This condenser, which works with reflux, discharges through the piping I8 a gaseous and cooled fraction of practically dry ammonia and through the piping 21 a slightly ammoniacal condensate which passes to the distillation column 28. Said column delivers, on the one hand, a phlegm which is enriched in ammonia and which is returned to the condenser I5 through the piping 32 and, on the other hand, a totally exhausted liquor which is removed through the piping 33 and through the exchanger 2I. Owing to said arrangement the whole quantity of water vaporized in the saturator is found again at 34 while the whole excess of ammonia which is practically free from moisture leaves through the piping I8. This ammonia receives through the reducing valve 23 an added portion of fresh gas corresponding exactly to What was absorbed in the saturator, then returns to the saturator through the piping 20 after comheating in the exchanger 2I. Finally, the conagar-4,040

5 tinuoustraining; 25 makes it possible to remove theuncondensab portions,the-ammonia hich is so carried forth being-recoveredthrough bub-- blin'g' through the phosphoric aeid' c'ontained in tlieva't'Z.

when the range of temperatures which under the totalpressure which has been chosen makes it possible 'to'obtainjthe desired ammonization rate for the mixture-which is treated "has been determined experimentally asexplained in the introduction to the present description, the control oi'the-operation essentiallyconsists in maintaining constant the pressure which "has beenchosen and the temperature of the vapour leaving the saturator.

The pressure will be maintained "automatically irrespectivel yiof the-rateof working-owing to the presence of the reducing valve '23 calibrated'to hold the pressure in the system to that previously chosen.

On'the other hand, the temperature of the atmosphere of the 'saturator 'isautomatically maintained constant owing to the fact that, on the one hand, the booster 'l 9'wli'ich controls the rate of circulation is driven "through the same motor 3'5which drives the measuring device 4, land I l-which, once the transmission ratio between said motor and the booster has been adjusted so that the "quantity of ammonia forced into the piping at every moment "corresponds in the requiredratio to the quantities "of materials de-v livered by "the measuring device while taking into account the necessary excess, insures the inv-ariability of said ratioand that, on the other hand, the governor 26 controlled by thepyrometer makes it possible .to maintain constant the composition of the gaseous fraction leaving the condenser [5, the combination of both said arrangements making it possible to keep an invariable composition ratio (ammonia) :(Water) in the atmosphere of the saturator.

The steam governor 30 acting according to the indications. of the pyrometer 3| facilitates the working of the system: pyrometer 25-governor 26 and makes it possible simultaneously to reduce the consumption of steam to a minimum.

Through operating according to the invention, it has been possible, while using the starting material in the following proportions:

161 kilograms of anhydrous ammonia,

405 kilograms of nitric acid of normal concentration,

515 kilograms of phosphoric acid produced by the attack of phosphate through sulphuric acid, and

310 kilograms of rich potassium chloride,

to obtain a thin paste which, after dehydration,

leaves 1,000 kilograms of a ternary fertilizer titrating:

18% of partly ammoniacal and partly nitric nitrogen,

18% of water soluble P205,

18% of K20.

For this operation the temperature of the bath was maintained in the neighborhood of 120 C.

When operating according to the invention, the following advantage are obtained:

(1) The proportioning and the addition of the starting materials to be ammonized being efiected at the head of the plant, the final thin paste reproduces at every moment the proportions which were delivered without it being necessary to perform any analytic control or any adjustment of the .titrations in the pourseoi the -manuacture:-

Consequently, any variation in the rate :or the drawing on o eration with respectto that of the saturation brings no change intheicompositionroi the thin paste which is drawn'ofi except a slight fluctuation of the moisture, which is of no importance. It is thus possible to interrupt com pletely the drawing off operation, for instance for the periodical cleaning of the granulating an'd drying app'aratus without modifying infanythihg the working regime of thesaturatonwhieh would not be possible if the-addition of "potash wereien footed after'theammonization. '(2-) immediately after their introduction :inw the' saturator, the starting materials are-diluted in 'a large mass 4 of saturated pro'd1i'ct';' the acidity: disappears immediately and the -:c'onversion' ls so to say instantaneous. The speed of "the reaetlon is the best obstacle to the natural development o'r the "crystals -so that "the obtained thin pas'te' i's homogeneou "and fiuid, which circumstanceis favourable-to its "later granulation. (3') Owing to the operation in an alkalinemedium and at a reduced temperature no "decompositionis to'be feared 'There is 'noevolu tion of fluorinated compounds supplied through the phosphoric acid nor nitrous decomposition nor reactionof the nitrate which has formed on the chloride, nor volatilization of ammoniumchloride nor any other similar prejudicial reaction. Correlatively, the vapour phase con tains only ammonia and water which makes it possible to construct the equipment following "the saturatorwith ordin'ar'ymaterials. Y is (4) No mother-liquor is produced and up to the drawing off operation, every operation is carried out in aclosed'vessel which'make's it possible to obtain the highest yields.

(5) The calorific power of the acids is used to I the utmost so that with starting materials of a current concentration a strongly dehydrated paste is obtained which is a chief condition for an economical drying operation.

(6) The consumption of energy even while taking into account the recompression oi the ammonia and the consumption of vapour, which is practically limited to the exhausting of the condensate, are exceedingly reduced.

('7) The control is simple and can be rendered automatic which entails a saving of man power.

What I claim is:

l; A method of manufacturing concentrated and highly soluble ternary fertilizers from raw materials including phosphoric acid and nitric acid solutions, potassium chloride and gaseous ammonia, which comprises maintaining in a closed reaction container, at a temperature well above the normal boiling point of water and under a substantially constant pressure a large and relatively deep mass of a fluid aqueous paste previously formed by combining such materials therein, continuously combining relatively small streams of said materials into said mass by introducing potassium chloride with phosphoric acid solution into an upper zone of the mass, introducing nitric acid solution at a remote point into an intermediate zone of the mass, introducing the ammonia under pressure into a bottom zone of'the mass and bubbling it through the mass at a rate exceeding that required to ammonizethe nitric acid inflow and diammonize completely the phosphoric acid inflow, thereby keeping substantially the entire mass well agitated and distinctly alkaline and causing immediate ammonization of the infiowing acids so as to avoid degradations within themass, by regulating the excess ammonia inflow regulating the temperature of the mass and its steam pressure so that it forms continuously as a fluid aqueous paste of crystalline salts in a normally liquid aqueous medium, and withdrawing. from the bottom of the mass surplus paste thus formed having its phosphate content completely diammonized.

2. A method of manufacturing concentrated and highly soluble ternary fertilizers from raw materials, including phosphoric acid and nitric acid solutions, potassium chloride and gaseous ammonia, which comprises, while maintaining in a closed reaction container a large mass of a fluid aqueous paste previously formed by combining said materials and keeping the mass by the heat of reaction at a temperature well above the normal boiling point of Water, continuously combining proportional streams of said material into said mass by introducing the potassium chloride with the phosphoric acid solution into an upper zone thereof, introducing the nitric acid solution into an intermediate zone thereof at a point remote from the inflow of potassium chloride, introducing the ammonia into a bottom zone of the mass and bubbling it through the mass at a rate substantially exceeding that required to ammonize the nitric acid inflow and diammonize completely the phosphoric acid inflow, continuously taking off from space in the container above said mass gases composed principally of ammonia and steam, in a closed circuit leading back to the ammonia intake continuously condensing steam from said gases and adding ammonia to the residual gas so as to provide enriched ammonia gas of substantially '8 uniform composition for the continuing ammonia inflow, by continuously regulating the pressure and flow rate of the enriched ammonia gas maintaining in th container a substantially constant pressure comprising a partial pressure of ammonia exceeding that required to diammonize the phosphoric acid inflow and so limiting the steaming rate that the reaction mass forms continuously as a fluid aqueous paste of crystalline salts in a normally liquid aqueous medium, and withdrawing surplus paste thus formed from the bottom of the mass with its phosphate content completely diammonized.

PHILIPPE KAIKINGER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,322,758 Carpenter Nov. 25, 1919 1,624,294 Wallace et al Apr. 12, 1927 1,625,807 Howard Apr. 26, 1927 1,962,185 Fauser June 12, 1934 1,971,563 'I-Iirschkind et al. Aug. 28, 1934 1,999,026 Tramm et al. Apr. 23, 1935 2,024,480 Short Dec. 1'7, 1935 2,025,916 Tramm Dec. 31, 1935 2,033,388 Moose Mar. '10, 1936 2,036,701 Kircher et al. Apr. 7, 1936 2,086,808 Kallam July 13, 1937 OTHER REFERENCES Ross et al., Preparation and Properties of the Ammonium Phosphate, reprint from Ind. and Eng. Chem, vol. 21, page 286, March 1929. 

1. A METHOD OF MANUFACTURING CONCENTRATED AND HIGHLY SOLUBLE TERNARY FERTILIZERS FROM RAW MATERIALS INCLUDING PHOSPHORIC ACID AND NITRIC ACID SOLUTIONS, POTASSIUM CHLORIDE AND GASEOUS AMMONIA, WHICH COMPRISES MAINTAINING IN A CLOSED REACTION CONTAINER, AT A TEMPERATURE WELL ABOVE THE NORMAL BOILING POINT OF WATER AND UNDER A SUBSTANTIALLY CONSTANT PRESSURE A LARGE AND RELATIVELY DEEP MASS OF A FLUID AQUEOUS PASTE PREVIOUSLY FORMED BY COMBINING SUCH MATERIALS THEREIN, CONTINUOUSLY COMBINING RELATIVELY SMALL STREAMS OF SAID MATERIALS INTO SAID MASS BY INTRODUCING POTASSIUM CHLORIDE WITH PHOSPHORIC ACID SOLUTION INTO AN UPPER ZONE OF THE MASS, INTRODUCING NITRIC ACID SOLUTION AT A REMOTE POINT INTO AN INTERMEDIATE ZONE OF THE MASS, INTRODUCING THE AMMONIA UNDER PRESSURE INTO A BOTTOM ZONE OF THE MASS AND BUBBLING IT THROUGH THE MASS AT A RATE EXCEEDING THAT REQUIRED TO AMMONIZE THE NITRIC ACID INFLOW AND DIAMMONIZE COMPLETELY THE PHOSPHORIC ACID INFLOW, THEREBY KEEPING SUBSTANTIALLY THE ENTIRE MASS WELL AGITATED AND DISTINCTLY ALKALINE AND CAUSING IMMEDIATE AMMONIZATION OF THE INFLOWING ACIDS SO AS TO AVOID DEGRADATIONS WITHIN THE MASS, BY REGULATING THE EXCESS AMMONIA INFLOW REGULATING THE TEMPERATURE OF THE MASS AND ITS STREAM PRESSURE SO THAT IT FORMS CONTINUOUSLY AS A FLUID AQUEOUS PASTE TO CRYSTALLINE SALTS IN A NORMALLY LIQUID AQUEOUS MEDIUM, AND WITHDRAWING FROM THE BOTTOM OF THE MASS SURPLUS PASTE THUS FORMED HAVING ITS PHOSPHATE CONTENT COMPLETELY DIAMMONIZED. 